Discussion of the implementations of VIRTIO specification
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From: Wei Wang <wei.w.wang@intel.com>
To: virtio-dev@lists.oasis-open.org, linux-kernel@vger.kernel.org,
	virtualization@lists.linux-foundation.org, kvm@vger.kernel.org,
	mst@redhat.com, cohuck@redhat.com, pasic@linux.ibm.com,
	borntraeger@de.ibm.com
Cc: pbonzini@redhat.com, dgilbert@redhat.com, wei.w.wang@intel.com
Subject: [virtio-dev] [PATCH v2 2/2] virtio-balloon: improve update_balloon_size_func
Date: Fri,  4 Jan 2019 15:11:53 +0800	[thread overview]
Message-ID: <1546585913-34804-3-git-send-email-wei.w.wang@intel.com> (raw)
In-Reply-To: <1546585913-34804-1-git-send-email-wei.w.wang@intel.com>

There is no need to update the balloon actual register when there is no
ballooning request. This patch avoids update_balloon_size when diff is 0.

Signed-off-by: Wei Wang <wei.w.wang@intel.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
---
 drivers/virtio/virtio_balloon.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 35ee762..af1e6d9 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -453,9 +453,12 @@ static void update_balloon_size_func(struct work_struct *work)
 			  update_balloon_size_work);
 	diff = towards_target(vb);
 
+	if (!diff)
+		return;
+
 	if (diff > 0)
 		diff -= fill_balloon(vb, diff);
-	else if (diff < 0)
+	else
 		diff += leak_balloon(vb, -diff);
 	update_balloon_size(vb);
 
-- 
2.7.4


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      parent reply	other threads:[~2019-01-04  7:47 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-04  7:11 [virtio-dev] [PATCH v2 0/2] virtio-balloon: tweak config_changed Wei Wang
2019-01-04  7:11 ` [virtio-dev] [PATCH v2 1/2] virtio-balloon: tweak config_changed implementation Wei Wang
2019-01-04 11:02   ` [virtio-dev] " Cornelia Huck
2019-01-04 11:26   ` [virtio-dev] " Halil Pasic
2019-01-04 15:44   ` [virtio-dev] " Michael S. Tsirkin
2019-01-05  3:32     ` [virtio-dev] " Wang, Wei W
2019-01-06  0:31       ` [virtio-dev] " Michael S. Tsirkin
2019-01-04  7:11 ` Wei Wang [this message]

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